nd is just the name of a discrete probability density function of 4 variables that I have defined earlier on. What I would really like to do is make this a 2 dimensional grid of squares where the value of nd is shown only by the color as opposed to both the color and the height; in other words, I don't want it to be 3D. Of course, I can rotate what I have to get a top down view, but this isn't exactly ideal:

I would much prefer to eliminate the third dimension altogether and have a simple grid where the output of nd is shown by a change in color of the squares in the 2D grid. Is this possible in Mathematica? If so, how would I do this? Thank you.